The ominous-sounding polar vortex has already swept down on much of the Northern Plains and the Midwest, bringing temperatures to their lowest in 20 years. But it’s not just the Midwest that will be experiencing the below-freezing temperatures; the vortex is expected to hit the East Coast as early as Monday night, bringing with it the risk of frostbite and hypothermia.

Temperatures in Chicago dropped to a record 16 degrees below zero on Monday, while Minneapolis saw temperatures reaching 18 below — not including a wind chill, which brought that down to 40 below. The case was, and will be, similar in nearly 24 other states spanning from the Southeast to the Northeast, as a front of cold air normally seen only in the arctic pushes through, CNN reported. “The big story was the wind chill factors,” Jim Keeney, a meteorologist at the National Weather Center’s regional headquarters in Kansas City, Mo., told The L.A. Times.

So what exactly is this polar vortex? According to AccuWeather, it’s a large pocket of (usually) the coldest air in the northern hemisphere, moving as high-speed winds in a counterclockwise direction — it’s known as a low-pressure system. It normally stays northwest of The U.S., near Siberia and the Arctic sea, but will occasionally move around during the winter. In this case, however, a large high-pressure system along the eastern Pacific is pushing further north than usual — it typically reaches Alaska — moving into the North Pole and pushing the vortex further south than usual. “The high pressure system, paired with the extensive snow cover over southern Canada and northern United States, is allowing the air to stay very cold,” Brett Anderson, a meteorologist with AccuWeather, said.

The cold weather, which is expected to last a few days, can be especially damaging to anyone who is outdoors. “It takes only minutes for exposed skin to become frostbitten if the temperature falls below 20 degrees Fahrenheit and the wind is blowing at 20 miles per hour or more,” Taizoon Baxamusa, MD, a spokesperson for the American Academy of Orthopaedic Surgeons, said prior to another cold spell in 2009. Exposure to cold temperatures can put a person at risk for hypothermia and frostbite, both of which are life-threatening. Here are some tips for spotting both conditions and for avoiding them altogether.

Hypothermia

Hypothermia is a dangerously low body temperature — typically below 95 degrees Fahrenheit. It can result in the loss of the ability to think and move, with some people even experiencing it unknowingly. Symptoms include drowsiness, weakness and loss of coordination, pale and cold skin, confusion, and uncontrollable shivering, according to the National Institutes of Health (NIH).

Frostbite

People with hypothermia are also likely to have frostbite as well. Initially characterized by a pins-and-needles feeling, followed by numbness, it also occurs when skin and body tissues are exposed to cold temperatures for an extended period of time. Other symptoms include hard skin and a lack of sensation. In more severe cases a person may experience blisters, gangrene, and damage to tendons, muscles, nerves, and bone.

Prevention

The best way to prevent sickness from the cold is to stay inside as much as possible. But upon going outside, the New York City Office of Emergency Management suggests:

· Wear a hat, hood, or scarf, as most heat is lost through the head.

· Wear layers, as they provide better insulation and warmth.

· Keep fingertips, earlobes, and noses covered if you go outside.

· Keep clothing dry; if a layer becomes wet, remove it.

Treatment

According to the NIH, a person with hypothermia should be taken to a warm room where they can heat up. If one isn’t available, they should be moved away from wind, and the person administering first aid should try to use their own body heat. Using warm compresses on the neck, chest wall, and groin, as well as giving them warm, sweetened, non-alcoholic beverages — only if they are able to drink — can also help.

When it comes to frostbite, it’s very important not to use direct heat, such as a radiator or campfire, or to rub or massage the frostbitten areas. Instead, the person’s affected areas should be soaked in warm (never hot) water. Warm clothes can also be placed on affected areas. Additionally, the thawed areas should not be moved. For both hypothermia and frostbite, it’s essential that a person doesn’t smoke or drink alcohol, as both can affect blood circulation.